Modern vehicles use wireless key fobs that restrict both interior access as well as the ability to operate the vehicle. Authorized vehicle users can carry the wireless key fobs and as they approach the vehicle it can determine whether the unique wireless signal transmitted by the key fob is authorized for access and/or operation. If so, the vehicle user can enter and subsequently start the vehicle. Before the vehicle user can start the vehicle, it determines whether or not the key fob is located inside the vehicle. Given that the threshold for the determination of being inside of or outside of the vehicle can be relatively small, resolving the location of the key fob in the vehicle may call for a high degree of accuracy. Presently, PEPS systems and key fobs can use wireless signals that fall on the low end of the frequency spectrum (e.g., ˜30-400 kHz) to resolve location. Such signals have relatively long wavelengths and dissipate quickly, which function well to accurately determine a distance value between the key fob and the vehicle.
However, modern vehicles are more frequently becoming equipped with other wireless communications capabilities than those currently used by the PEPS systems. For example, the vehicles often can have an ability to facilitate communication with other wireless devices via BLUETOOTH™ LE or Wi-Fi in addition to the low frequency signals used by the current PEPS system. It may be helpful to replace the dedicated low-frequency signal transmission presently used by PEPS systems with the BLUETOOTH™ LE or Wi-Fi communication technologies. But BLUETOOTH™ LE and Wi-Fi operate using wireless frequencies that are much higher (2.4 GHz) than what the PEPS system presently relies on. These higher-frequency wireless signals may not produce a very accurate estimate of key fob location within the vehicle as they have a tendency to diffract and reflect off of interior surfaces in the vehicle and the surroundings. These reflected signals may be unsuitable to accurately determine the position of the key fob.